/*
** $Id: ldebug.c,v 2.121 2016/10/19 12:32:10 roberto Exp $
** Debug Interface
** See Copyright Notice in lua.h
*/

#define ldebug_c
#define LUA_CORE

#include "lprefix.h"


#include <stdarg.h>
#include <stddef.h>
#include <string.h>

#include "lua.h"

#include "lapi.h"
#include "lcode.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lvm.h"



#define noLuaClosure(f)     ((f) == NULL || (f)->c.tt == LUA_TCCL)


/* Active Lua function (given call info) */
#define ci_func(ci)     (clLvalue((ci)->func))


static const char *funcnamefromcode(lua_State *L, CallInfo *ci,
                                    const char **name);


static int currentpc(CallInfo *ci)
{
    lua_assert(isLua(ci));
    return pcRel(ci->u.l.savedpc, ci_func(ci)->p);
}


static int currentline(CallInfo *ci)
{
    return getfuncline(ci_func(ci)->p, currentpc(ci));
}


/*
** If function yielded, its 'func' can be in the 'extra' field. The
** next function restores 'func' to its correct value for debugging
** purposes. (It exchanges 'func' and 'extra'; so, when called again,
** after debugging, it also "re-restores" ** 'func' to its altered value.
*/
static void swapextra(lua_State *L)
{
    if (L->status == LUA_YIELD)
    {
        CallInfo *ci = L->ci;  /* get function that yielded */
        StkId temp = ci->func;  /* exchange its 'func' and 'extra' values */
        ci->func = restorestack(L, ci->extra);
        ci->extra = savestack(L, temp);
    }
}


/*
** This function can be called asynchronously (e.g. during a signal).
** Fields 'oldpc', 'basehookcount', and 'hookcount' (set by
** 'resethookcount') are for debug only, and it is no problem if they
** get arbitrary values (causes at most one wrong hook call). 'hookmask'
** is an atomic value. We assume that pointers are atomic too (e.g., gcc
** ensures that for all platforms where it runs). Moreover, 'hook' is
** always checked before being called (see 'luaD_hook').
*/
LUA_API void lua_sethook(lua_State *L, lua_Hook func, int mask, int count)
{
    if (func == NULL || mask == 0)    /* turn off hooks? */
    {
        mask = 0;
        func = NULL;
    }

    if (isLua(L->ci))
        L->oldpc = L->ci->u.l.savedpc;

    L->hook = func;
    L->basehookcount = count;
    resethookcount(L);
    L->hookmask = cast_byte(mask);
}


LUA_API lua_Hook lua_gethook(lua_State *L)
{
    return L->hook;
}


LUA_API int lua_gethookmask(lua_State *L)
{
    return L->hookmask;
}


LUA_API int lua_gethookcount(lua_State *L)
{
    return L->basehookcount;
}


LUA_API int lua_getstack(lua_State *L, int level, lua_Debug *ar)
{
    int status;
    CallInfo *ci;

    if (level < 0) return 0;  /* invalid (negative) level */

    lua_lock(L);

    for (ci = L->ci; level > 0 && ci != &L->base_ci; ci = ci->previous)
        level--;

    if (level == 0 && ci != &L->base_ci)    /* level found? */
    {
        status = 1;
        ar->i_ci = ci;
    }
    else status = 0;  /* no such level */

    lua_unlock(L);
    return status;
}


static const char *upvalname(Proto *p, int uv)
{
    TString *s = check_exp(uv < p->sizeupvalues, p->upvalues[uv].name);

    if (s == NULL) return "?";
    else return getstr(s);
}


static const char *findvararg(CallInfo *ci, int n, StkId *pos)
{
    int nparams = clLvalue(ci->func)->p->numparams;

    if (n >= cast_int(ci->u.l.base - ci->func) - nparams)
        return NULL;  /* no such vararg */
    else
    {
        *pos = ci->func + nparams + n;
        return "(*vararg)";  /* generic name for any vararg */
    }
}


static const char *findlocal(lua_State *L, CallInfo *ci, int n,
                             StkId *pos)
{
    const char *name = NULL;
    StkId base;

    if (isLua(ci))
    {
        if (n < 0)  /* access to vararg values? */
            return findvararg(ci, -n, pos);
        else
        {
            base = ci->u.l.base;
            name = luaF_getlocalname(ci_func(ci)->p, n, currentpc(ci));
        }
    }
    else
        base = ci->func + 1;

    if (name == NULL)    /* no 'standard' name? */
    {
        StkId limit = (ci == L->ci) ? L->top : ci->next->func;

        if (limit - base >= n && n > 0)  /* is 'n' inside 'ci' stack? */
            name = "(*temporary)";  /* generic name for any valid slot */
        else
            return NULL;  /* no name */
    }

    *pos = base + (n - 1);
    return name;
}


LUA_API const char *lua_getlocal(lua_State *L, const lua_Debug *ar, int n)
{
    const char *name;
    lua_lock(L);
    swapextra(L);

    if (ar == NULL)    /* information about non-active function? */
    {
        if (!isLfunction(L->top - 1))  /* not a Lua function? */
            name = NULL;
        else  /* consider live variables at function start (parameters) */
            name = luaF_getlocalname(clLvalue(L->top - 1)->p, n, 0);
    }
    else    /* active function; get information through 'ar' */
    {
        StkId pos = NULL;  /* to avoid warnings */
        name = findlocal(L, ar->i_ci, n, &pos);

        if (name)
        {
            setobj2s(L, L->top, pos);
            api_incr_top(L);
        }
    }

    swapextra(L);
    lua_unlock(L);
    return name;
}


LUA_API const char *lua_setlocal(lua_State *L, const lua_Debug *ar, int n)
{
    StkId pos = NULL;  /* to avoid warnings */
    const char *name;
    lua_lock(L);
    swapextra(L);
    name = findlocal(L, ar->i_ci, n, &pos);

    if (name)
    {
        setobjs2s(L, pos, L->top - 1);
        L->top--;  /* pop value */
    }

    swapextra(L);
    lua_unlock(L);
    return name;
}


static void funcinfo(lua_Debug *ar, Closure *cl)
{
    if (noLuaClosure(cl))
    {
        ar->source = "=[C]";
        ar->linedefined = -1;
        ar->lastlinedefined = -1;
        ar->what = "C";
    }
    else
    {
        Proto *p = cl->l.p;
        ar->source = p->source ? getstr(p->source) : "=?";
        ar->linedefined = p->linedefined;
        ar->lastlinedefined = p->lastlinedefined;
        ar->what = (ar->linedefined == 0) ? "main" : "Lua";
    }

    luaO_chunkid(ar->short_src, ar->source, LUA_IDSIZE);
}


static void collectvalidlines(lua_State *L, Closure *f)
{
    if (noLuaClosure(f))
    {
        setnilvalue(L->top);
        api_incr_top(L);
    }
    else
    {
        int i;
        TValue v;
        int *lineinfo = f->l.p->lineinfo;
        Table *t = luaH_new(L);  /* new table to store active lines */
        sethvalue(L, L->top, t);  /* push it on stack */
        api_incr_top(L);
        setbvalue(&v, 1);  /* boolean 'true' to be the value of all indices */

        for (i = 0; i < f->l.p->sizelineinfo; i++)  /* for all lines with code */
            luaH_setint(L, t, lineinfo[i], &v);  /* table[line] = true */
    }
}


static const char *getfuncname(lua_State *L, CallInfo *ci, const char **name)
{
    if (ci == NULL)  /* no 'ci'? */
        return NULL;  /* no info */
    else if (ci->callstatus & CIST_FIN)    /* is this a finalizer? */
    {
        *name = "__gc";
        return "metamethod";  /* report it as such */
    }
    /* calling function is a known Lua function? */
    else if (!(ci->callstatus & CIST_TAIL) && isLua(ci->previous))
        return funcnamefromcode(L, ci->previous, name);
    else return NULL;  /* no way to find a name */
}


static int auxgetinfo(lua_State *L, const char *what, lua_Debug *ar,
                      Closure *f, CallInfo *ci)
{
    int status = 1;

    for (; *what; what++)
    {
        switch (*what)
        {
            case 'S':
            {
                funcinfo(ar, f);
                break;
            }

            case 'l':
            {
                ar->currentline = (ci && isLua(ci)) ? currentline(ci) : -1;
                break;
            }

            case 'u':
            {
                ar->nups = (f == NULL) ? 0 : f->c.nupvalues;

                if (noLuaClosure(f))
                {
                    ar->isvararg = 1;
                    ar->nparams = 0;
                }
                else
                {
                    ar->isvararg = f->l.p->is_vararg;
                    ar->nparams = f->l.p->numparams;
                }

                break;
            }

            case 't':
            {
                ar->istailcall = (ci) ? ci->callstatus & CIST_TAIL : 0;
                break;
            }

            case 'n':
            {
                ar->namewhat = getfuncname(L, ci, &ar->name);

                if (ar->namewhat == NULL)
                {
                    ar->namewhat = "";  /* not found */
                    ar->name = NULL;
                }

                break;
            }

            case 'L':
            case 'f':  /* handled by lua_getinfo */
                break;

            default:
                status = 0;  /* invalid option */
        }
    }

    return status;
}


LUA_API int lua_getinfo(lua_State *L, const char *what, lua_Debug *ar)
{
    int status;
    Closure *cl;
    CallInfo *ci;
    StkId func;
    lua_lock(L);
    swapextra(L);

    if (*what == '>')
    {
        ci = NULL;
        func = L->top - 1;
        api_check(L, ttisfunction(func), "function expected");
        what++;  /* skip the '>' */
        L->top--;  /* pop function */
    }
    else
    {
        ci = ar->i_ci;
        func = ci->func;
        lua_assert(ttisfunction(ci->func));
    }

    cl = ttisclosure(func) ? clvalue(func) : NULL;
    status = auxgetinfo(L, what, ar, cl, ci);

    if (strchr(what, 'f'))
    {
        setobjs2s(L, L->top, func);
        api_incr_top(L);
    }

    swapextra(L);  /* correct before option 'L', which can raise a mem. error */

    if (strchr(what, 'L'))
        collectvalidlines(L, cl);

    lua_unlock(L);
    return status;
}


/*
** {======================================================
** Symbolic Execution
** =======================================================
*/

static const char *getobjname(Proto *p, int lastpc, int reg,
                              const char **name);


/*
** find a "name" for the RK value 'c'
*/
static void kname(Proto *p, int pc, int c, const char **name)
{
    if (ISK(c))    /* is 'c' a constant? */
    {
        TValue *kvalue = &p->k[INDEXK(c)];

        if (ttisstring(kvalue))    /* literal constant? */
        {
            *name = svalue(kvalue);  /* it is its own name */
            return;
        }

        /* else no reasonable name found */
    }
    else    /* 'c' is a register */
    {
        const char *what = getobjname(p, pc, c, name); /* search for 'c' */

        if (what && *what == 'c')    /* found a constant name? */
        {
            return;  /* 'name' already filled */
        }

        /* else no reasonable name found */
    }

    *name = "?";  /* no reasonable name found */
}


static int filterpc(int pc, int jmptarget)
{
    if (pc < jmptarget)  /* is code conditional (inside a jump)? */
        return -1;  /* cannot know who sets that register */
    else return pc;  /* current position sets that register */
}


/*
** try to find last instruction before 'lastpc' that modified register 'reg'
*/
static int findsetreg(Proto *p, int lastpc, int reg)
{
    int pc;
    int setreg = -1;  /* keep last instruction that changed 'reg' */
    int jmptarget = 0;  /* any code before this address is conditional */

    for (pc = 0; pc < lastpc; pc++)
    {
        Instruction i = p->code[pc];
        OpCode op = GET_OPCODE(i);
        int a = GETARG_A(i);

        switch (op)
        {
            case OP_LOADNIL:
            {
                int b = GETARG_B(i);

                if (a <= reg && reg <= a + b)  /* set registers from 'a' to 'a+b' */
                    setreg = filterpc(pc, jmptarget);

                break;
            }

            case OP_TFORCALL:
            {
                if (reg >= a + 2)  /* affect all regs above its base */
                    setreg = filterpc(pc, jmptarget);

                break;
            }

            case OP_CALL:
            case OP_TAILCALL:
            {
                if (reg >= a)  /* affect all registers above base */
                    setreg = filterpc(pc, jmptarget);

                break;
            }

            case OP_JMP:
            {
                int b = GETARG_sBx(i);
                int dest = pc + 1 + b;

                /* jump is forward and do not skip 'lastpc'? */
                if (pc < dest && dest <= lastpc)
                {
                    if (dest > jmptarget)
                        jmptarget = dest;  /* update 'jmptarget' */
                }

                break;
            }

            default:
                if (testAMode(op) && reg == a)  /* any instruction that set A */
                    setreg = filterpc(pc, jmptarget);

                break;
        }
    }

    return setreg;
}


static const char *getobjname(Proto *p, int lastpc, int reg,
                              const char **name)
{
    int pc;
    *name = luaF_getlocalname(p, reg + 1, lastpc);

    if (*name)  /* is a local? */
        return "local";

    /* else try symbolic execution */
    pc = findsetreg(p, lastpc, reg);

    if (pc != -1)    /* could find instruction? */
    {
        Instruction i = p->code[pc];
        OpCode op = GET_OPCODE(i);

        switch (op)
        {
            case OP_MOVE:
            {
                int b = GETARG_B(i);  /* move from 'b' to 'a' */

                if (b < GETARG_A(i))
                    return getobjname(p, pc, b, name);  /* get name for 'b' */

                break;
            }

            case OP_GETTABUP:
            case OP_GETTABLE:
            {
                int k = GETARG_C(i);  /* key index */
                int t = GETARG_B(i);  /* table index */
                const char *vn = (op == OP_GETTABLE)  /* name of indexed variable */
                                 ? luaF_getlocalname(p, t + 1, pc)
                                 : upvalname(p, t);
                kname(p, pc, k, name);
                return (vn && strcmp(vn, LUA_ENV) == 0) ? "global" : "field";
            }

            case OP_GETUPVAL:
            {
                *name = upvalname(p, GETARG_B(i));
                return "upvalue";
            }

            case OP_LOADK:
            case OP_LOADKX:
            {
                int b = (op == OP_LOADK) ? GETARG_Bx(i)
                        : GETARG_Ax(p->code[pc + 1]);

                if (ttisstring(&p->k[b]))
                {
                    *name = svalue(&p->k[b]);
                    return "constant";
                }

                break;
            }

            case OP_SELF:
            {
                int k = GETARG_C(i);  /* key index */
                kname(p, pc, k, name);
                return "method";
            }

            default:
                break;  /* go through to return NULL */
        }
    }

    return NULL;  /* could not find reasonable name */
}


/*
** Try to find a name for a function based on the code that called it.
** (Only works when function was called by a Lua function.)
** Returns what the name is (e.g., "for iterator", "method",
** "metamethod") and sets '*name' to point to the name.
*/
static const char *funcnamefromcode(lua_State *L, CallInfo *ci,
                                    const char **name)
{
    TMS tm = (TMS)0;  /* (initial value avoids warnings) */
    Proto *p = ci_func(ci)->p;  /* calling function */
    int pc = currentpc(ci);  /* calling instruction index */
    Instruction i = p->code[pc];  /* calling instruction */

    if (ci->callstatus & CIST_HOOKED)    /* was it called inside a hook? */
    {
        *name = "?";
        return "hook";
    }

    switch (GET_OPCODE(i))
    {
        case OP_CALL:
        case OP_TAILCALL:
            return getobjname(p, pc, GETARG_A(i), name);  /* get function name */

        case OP_TFORCALL:    /* for iterator */
        {
            *name = "for iterator";
            return "for iterator";
        }

        /* other instructions can do calls through metamethods */
        case OP_SELF:
        case OP_GETTABUP:
        case OP_GETTABLE:
            tm = TM_INDEX;
            break;

        case OP_SETTABUP:
        case OP_SETTABLE:
            tm = TM_NEWINDEX;
            break;

        case OP_ADD:
        case OP_SUB:
        case OP_MUL:
        case OP_MOD:
        case OP_POW:
        case OP_DIV:
        case OP_IDIV:
        case OP_BAND:
        case OP_BOR:
        case OP_BXOR:
        case OP_SHL:
        case OP_SHR:
        {
            int offset = cast_int(GET_OPCODE(i)) - cast_int(OP_ADD);  /* ORDER OP */
            tm = cast(TMS, offset + cast_int(TM_ADD));  /* ORDER TM */
            break;
        }

        case OP_UNM:
            tm = TM_UNM;
            break;

        case OP_BNOT:
            tm = TM_BNOT;
            break;

        case OP_LEN:
            tm = TM_LEN;
            break;

        case OP_CONCAT:
            tm = TM_CONCAT;
            break;

        case OP_EQ:
            tm = TM_EQ;
            break;

        case OP_LT:
            tm = TM_LT;
            break;

        case OP_LE:
            tm = TM_LE;
            break;

        default:
            return NULL;  /* cannot find a reasonable name */
    }

    *name = getstr(G(L)->tmname[tm]);
    return "metamethod";
}

/* }====================================================== */



/*
** The subtraction of two potentially unrelated pointers is
** not ISO C, but it should not crash a program; the subsequent
** checks are ISO C and ensure a correct result.
*/
static int isinstack(CallInfo *ci, const TValue *o)
{
    ptrdiff_t i = o - ci->u.l.base;
    return (0 <= i && i < (ci->top - ci->u.l.base) && ci->u.l.base + i == o);
}


/*
** Checks whether value 'o' came from an upvalue. (That can only happen
** with instructions OP_GETTABUP/OP_SETTABUP, which operate directly on
** upvalues.)
*/
static const char *getupvalname(CallInfo *ci, const TValue *o,
                                const char **name)
{
    LClosure *c = ci_func(ci);
    int i;

    for (i = 0; i < c->nupvalues; i++)
    {
        if (c->upvals[i]->v == o)
        {
            *name = upvalname(c->p, i);
            return "upvalue";
        }
    }

    return NULL;
}


static const char *varinfo(lua_State *L, const TValue *o)
{
    const char *name = NULL;  /* to avoid warnings */
    CallInfo *ci = L->ci;
    const char *kind = NULL;

    if (isLua(ci))
    {
        kind = getupvalname(ci, o, &name);  /* check whether 'o' is an upvalue */

        if (!kind && isinstack(ci, o))  /* no? try a register */
            kind = getobjname(ci_func(ci)->p, currentpc(ci),
                              cast_int(o - ci->u.l.base), &name);
    }

    return (kind) ? luaO_pushfstring(L, " (%s '%s')", kind, name) : "";
}


l_noret luaG_typeerror(lua_State *L, const TValue *o, const char *op)
{
    const char *t = luaT_objtypename(L, o);
    luaG_runerror(L, "attempt to %s a %s value%s", op, t, varinfo(L, o));
}


l_noret luaG_concaterror(lua_State *L, const TValue *p1, const TValue *p2)
{
    if (ttisstring(p1) || cvt2str(p1)) p1 = p2;

    luaG_typeerror(L, p1, "concatenate");
}


l_noret luaG_opinterror(lua_State *L, const TValue *p1,
                        const TValue *p2, const char *msg)
{
    lua_Number temp;

    if (!tonumber(p1, &temp))  /* first operand is wrong? */
        p2 = p1;  /* now second is wrong */

    luaG_typeerror(L, p2, msg);
}


/*
** Error when both values are convertible to numbers, but not to integers
*/
l_noret luaG_tointerror(lua_State *L, const TValue *p1, const TValue *p2)
{
    lua_Integer temp;

    if (!tointeger(p1, &temp))
        p2 = p1;

    luaG_runerror(L, "number%s has no integer representation", varinfo(L, p2));
}


l_noret luaG_ordererror(lua_State *L, const TValue *p1, const TValue *p2)
{
    const char *t1 = luaT_objtypename(L, p1);
    const char *t2 = luaT_objtypename(L, p2);

    if (strcmp(t1, t2) == 0)
        luaG_runerror(L, "attempt to compare two %s values", t1);
    else
        luaG_runerror(L, "attempt to compare %s with %s", t1, t2);
}


/* add src:line information to 'msg' */
const char *luaG_addinfo(lua_State *L, const char *msg, TString *src,
                         int line)
{
    char buff[LUA_IDSIZE];

    if (src)
        luaO_chunkid(buff, getstr(src), LUA_IDSIZE);
    else    /* no source available; use "?" instead */
    {
        buff[0] = '?';
        buff[1] = '\0';
    }

    return luaO_pushfstring(L, "%s:%d: %s", buff, line, msg);
}


l_noret luaG_errormsg(lua_State *L)
{
    if (L->errfunc != 0)    /* is there an error handling function? */
    {
        StkId errfunc = restorestack(L, L->errfunc);
        setobjs2s(L, L->top, L->top - 1);  /* move argument */
        setobjs2s(L, L->top - 1, errfunc);  /* push function */
        L->top++;  /* assume EXTRA_STACK */
        luaD_callnoyield(L, L->top - 2, 1);  /* call it */
    }

    luaD_throw(L, LUA_ERRRUN);
}


l_noret luaG_runerror(lua_State *L, const char *fmt, ...)
{
    CallInfo *ci = L->ci;
    const char *msg;
    va_list argp;
    va_start(argp, fmt);
    msg = luaO_pushvfstring(L, fmt, argp);  /* format message */
    va_end(argp);

    if (isLua(ci))  /* if Lua function, add source:line information */
        luaG_addinfo(L, msg, ci_func(ci)->p->source, currentline(ci));

    luaG_errormsg(L);
}


void luaG_traceexec(lua_State *L)
{
    CallInfo *ci = L->ci;
    lu_byte mask = L->hookmask;
    int counthook = (--L->hookcount == 0 && (mask & LUA_MASKCOUNT));

    if (counthook)
        resethookcount(L);  /* reset count */
    else if (!(mask & LUA_MASKLINE))
        return;  /* no line hook and count != 0; nothing to be done */

    if (ci->callstatus & CIST_HOOKYIELD)    /* called hook last time? */
    {
        ci->callstatus &= ~CIST_HOOKYIELD;  /* erase mark */
        return;  /* do not call hook again (VM yielded, so it did not move) */
    }

    if (counthook)
        luaD_hook(L, LUA_HOOKCOUNT, -1);  /* call count hook */

    if (mask & LUA_MASKLINE)
    {
        Proto *p = ci_func(ci)->p;
        int npc = pcRel(ci->u.l.savedpc, p);
        int newline = getfuncline(p, npc);

        if (npc == 0 ||  /* call linehook when enter a new function, */
                ci->u.l.savedpc <= L->oldpc ||  /* when jump back (loop), or when */
                newline != getfuncline(p, pcRel(L->oldpc, p)))  /* enter a new line */
            luaD_hook(L, LUA_HOOKLINE, newline);  /* call line hook */
    }

    L->oldpc = ci->u.l.savedpc;

    if (L->status == LUA_YIELD)    /* did hook yield? */
    {
        if (counthook)
            L->hookcount = 1;  /* undo decrement to zero */

        ci->u.l.savedpc--;  /* undo increment (resume will increment it again) */
        ci->callstatus |= CIST_HOOKYIELD;  /* mark that it yielded */
        ci->func = L->top - 1;  /* protect stack below results */
        luaD_throw(L, LUA_YIELD);
    }
}

